// Give a hard error if `--config` or `RUST_BOOTSTRAP_CONFIG` are set to a missing path,
// but not if `config.toml` hasn't been created.
let mut toml = if !using_default_path || toml_path.exists() {
// Give a hard error if `--config` or `RUST_BOOTSTRAP_CONFIG` are set to a missing path,
// but not if `config.toml` hasn't been created.
let mut toml = if !using_default_path || toml_path.exists() {